The present invention generally relates to electric motors and in particular to a system and method for facilitating the integration of an electric motor with an electromagnetic brake.
Electromagnetic disk brakes are widely used in a variety of applications such as dynamic brakes for motor input shafts and/or output shafts and as static or xe2x80x9choldingxe2x80x9d brakes for motors and the like. A typical electromagnetic disk brake of this type includes a friction disk that is coupled with the shaft so as to be movable axially relative to the shaft but to be rotationally fixed relative to the shaft. In static braking applications, the brake is applied by compressing the friction disk between a stationary reaction plate and an axially movable armature plate to provide the desired holding action, and the brake is released by energizing the electromagnet to retract the armature plate to allow the friction disk to rotate freely. In dynamic braking applications, the brake is applied while the shaft is rotating, either by energizing an electromagnetic actuator to overcome the force of a compression spring or by de-energizing a normally energized actuator to permit the compression spring to apply the brake.
Electromagnetic disk brakes designed specifically for use with electric motors exhibit several disadvantages. Specifically, brakes of this type require a mounting plate for attaching the brake to the motor""s end shield. This mounting plate necessarily increases the size and weight of the brake, limiting the brake""s usefulness in some applications. Attachment of the brake to the motor end shield often requires modification of the existing end shield structure to accept the mounting plate, which tends to be labor intensive. Furthermore, when adding a brake to motors employing an internal fan for cooling, the brake is often mounted to the fan housing. Thus, the fan is positioned between the brake and the motor, preventing cooling to the brake. The heat produced by the brake during normal operation has a deleterious effect on the stopping and starting capacity of the brake. Additionally, the heat on the brake has a deleterious effect on the life of the brake and the motor.
Conventional manual brake release mechanisms typically have significant rotational play when the brake is actuated, leading to rattling and possibly to false actuation of indicator switches which are intended to be closed only upon manual brake release. Furthermore, the manual release mechanisms typically employed in electromagnetic brakes either utilize a two step process for providing an even pull on the armature plate or a one step process which only provides a pull on one side of the armature plate.
Therefore, there is an unmet need in the art to facilitate the integration of electric motors with electromagnetic brakes for decreasing cost, size and weight of the brake, while increasing efficiency of the brake.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the invention. It is intended to neither identify key or critical elements of the invention nor delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented later.
The present invention provides for a system and method that facilitates integration of an electric motor with an electromagnetic brake. The integral brake motor of the present invention includes a cylindrical frame coupled to a circular end shield and an integral field cup and front end shield. The circular end shield is located at a drive end of the motor while the integral field cup and front end shield is located opposite the drive end of the motor. Within the frame is an electrical core for providing energy to the motor. The electrical core consists of a stator and a rotor and any additional circuitry and wiring required to operate the motor. The rotor is coupled to a rotor shaft. The rotor shaft is supported by bearing assemblies located in both the circular end shield and the integral field cup and front end shield. In addition to functioning as an end shield for the motor, the integral field cup and front end shield functions as a field cup for the brake component. The integral field cup and front end shield houses an electromagnetic coil. The electromagnetic coil is operable to electrically engage and/or disengage the brake. The present invention provides for a system and method to accomplish this process.
According to one aspect of the present invention, an internal fan is coupled to the shaft of the motor and is positioned outside of the brake components. The fan is operable to provide cooling air to the motor as well as the brake, thereby improving the bearing life and efficiency of the motor, as well as the starting and stopping capacity of the brake.
According to another aspect of the present invention, a manual brake release mechanism is coupled to the integral field cup and front end shield. The brake release mechanism includes a lever and cam combination for manual engagement and disengagement of the brake. The brake release mechanism employs a one step operation to provide an even pull on the armature plate, which disengages the brake.
To the accomplishment of the foregoing and related ends, the invention then, comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other object, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.